Regiocontrolled synthesis of 3-substituted-6-trifluoromethyl-4(3H)-pyrimidinones

Direct reaction of a variety of N-monosubstituted benzamidines with 4,4,4-t rifluoroacetoacetate esters substituted at the 2-position with methyl, ethy l or methoxy afforded moderate to good yields of herbicidal 3-substituted-6 -trifluoromethyl-4(3H)-pyrimidinones nones. Lower yields were obtained with the corresponding 4,4-difluoroacetoacetate esters and the reaction failed with nonfluorinated beta -ketoesters. In addition to benzamidines, 3- and 4 -pyridylcarboxamidines reacted successfully. The reaction tolerated propyl, allyl, propargyl and phenyl substituents on the amidine nitrogen. (C) 2001 Elsevier Science Ltd. All rights reserved.